1. Field of the Invention
The invention relates to a method for separately gaining skin-free belly flaps of fish as well as an apparatus for integration into a fish filleting machine for performing this method, in which each belly flap is severed from the fillets by a longitudinal cut performed substantially in the region of and parallel to the vertebral column as well as perpendicular to the plane of symmetry of the fish, said longitudinal cut extending up to either one of the vertebral appendages and ribs, and by a cross cut following the longitudinal cut and being performed substantially perpendicular to the vertebral column of the fish.
2. Prior Art
The increasing population of the world, on the one hand, and the limited protein resources, on the other, make it a permanent requirement to improve the degree of exploitation of these resources. At the same time, it is very important to optimize the commercial effect by improving the quality of the products concerned.
As far as the exploitation of fish as raw material is concerned, it is known to perform e.g. a separation of the fillets and aim at obtaining vendable products which will gain the possibly highest price, corresponding to their quality, which products are achieved by removing portions which are naturally of lower quality. For this reason, the meat portions of fish, which are situated in the region of the ribs and vertebral appendages surrounding the belly cavity, in other words the belly flaps, are severed by including the pinbones extending into the fillet meat approximately on the level of the lateral portions of the vertebral column. Such severing is performed in order to obtain a "bone-free fillet" which can be offered as a product of highest quality.
German Patent No. 24 60 447 discloses a method and a filleting machine serving this goal. In the course of normal filleting, but before the ribs and the lateral vertebral appendages are cut free by one horizontal cut in the region of the row of pinbones and by one cross cut at the end of the belly cavity, a separation of the belly flap is performed, which may then be cut free by a normal rib cut. The rib-free belly flap obtained separately in this manner is normally used for gaining fish flesh, which, even though it presents a product of highest quality, is considered to be of less value, due to its consistency and structure.
3. Objects of the Invention
It is the basic object of the invention to suggest a possibility of improving the economy of gaining fish protein.
It is a further essential object to offer the aforementioned belly flaps in the shape of pieces which, necessarily, have been skinned and, if possible, are supplied without bones.
It is yet another important object of the invention to perform such processing without additional expenditure on staff.